Messages in this thread | | | Date | Fri, 4 Mar 2005 15:29:02 -0800 | From | Andrew Morton <> | Subject | Re: [MC] [CHECKER] Do ext2, jfs and reiserfs respect mount -o sync/dirsync option? |
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Junfeng Yang <yjf@stanford.edu> wrote: > > > >From a quick parse, ext2 seems to be full of MS_SYNCHRONOUS holes, and > > there might be some O_SYNC ones there as well. > > I should be able to easily add O_SYNC check to FiSC. Several questions: > 1. Does O_SYNC apply to directory as well?
Only if you can open directores for writing ;)
> 2. For the same file, if I open twice, once with O_SYNC and another time > without, only writes through the O_SYNC fd will be sychonous, right?
Yes, O_SYNC is a per-fd thing.
> 3. I open a file w/o O_SYNC, issue a bunch of writes, then call > ioctl(FIOASYNC) to set the fd sync, then issure a second set of writes. > Only the second set of writes are synchronous?
FIOSYNC is unrelated to O_SYNC. OSYNC can only be set at open().
> btw, man page show that O_DSYNC and O_RSYNC are just O_SYNC. Is this true > for current linux kernel (2.6)?
The kernel only supports O_SYNC (equivalent behaviour to O_RSYNC|O_DSYNC). Perhaps glibc does a conversion.
> > So this wild scattergun patch probably does extra work and possibly extra > > I/O all over the place, but I'd be interested if Junfeng could give it a > > quick test. It's against 2.6.11. > > I checked 2.6.11 with your patch just now. Looks like the problem is > still there. If you need more information, let me know. Image is at > http://fisc.stanford.edu/bug2/crash-1.img.bz2. Below is the output from > e2fsck.
ugh. Thanks.
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